title: Glyphosate reduces urediniospore development and Puccinia psidii disease severity on Eucalyptus grandis.
abstract: BACKGROUND
  Recent studies have shown the effects of glyphosate drift on decreasing rust intensity on Eucalyptus grandis plants. However, the effects of the herbicide on Puccinia psidii initial development are unknown. In this study the systemic action of glyphosate on rust severity was evaluated on Eucalyptus plants maintained under greenhouse conditions. Urediniospore germination and apressorium formation on detached leaves and on water agar medium, previously treated with glyphosate, were also evaluated.
  
  
  RESULTS
  Rust severity and the number of urediniospores per leaf area were significantly reduced with increasing glyphosate doses, even on branches not directly treated with the herbicide, indicating a systemic effect of glyphosate on pathogen development. Similarly, higher glyphosate doses also reduced germination and apressorium formation on detached Eucalyptus leaves, regardless of the direct application of the product on the leaf limb or on the petiole base. Puccinia psidii urediniospore germination in water agar medium also decreased with increasing herbicide doses.
  
  
  CONCLUSIONS
  Reductions in germination and apressorium formation of P. psidii urediniospores with increasing glyphosate dose indicate that a lower severity and intensity of the disease may perhaps be due to blockage of the shikimic acid pathway in the fungal metabolic system.
authors.affiliation: Instituto de Ciências Agrárias, Universidade Federal de Minas Gerais, Montes Claros-MG, Brazil. ltuffi@ufmg.br
authors.forename: Leonardo D Tuffi
authors.initials: LD
authors.lastname: Santos
authors.forename: Rodrigo N
authors.initials: RN
authors.lastname: Graça
authors.forename: Acelino C
authors.initials: AC
authors.lastname: Alfenas
authors.forename: Francisco A
authors.initials: FA
authors.lastname: Ferreira
authors.forename: Christiane A D
authors.initials: CA
authors.lastname: Melo
authors.forename: Miler S
authors.initials: MS
authors.lastname: Machado
mesh_terms: D001487:Basidiomycota / Q000187:drug effects* / Q000254:growth & development; D005052:Eucalyptus / Q000382:microbiology*; D005659:Fungicides, Industrial / Q000494:pharmacology*; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D010935:Plant Diseases / Q000382:microbiology*; D013172:Spores, Fungal / Q000187:drug effects / Q000254:growth & development*; D000097797:Glyphosate
chemical_list: D005659:Fungicides, Industrial; D005998:Glycine; D000097797:Glyphosate